In decades past, colic treatment was actually a misnomer. "Treatment" consisted of waiting out the colic while offering sedative-like drugs to dampen a horse's misery. Either his body healed of its own accord, or he succumbed to death from overwhelming pain and shock. Veterinarians were reluctant to euthanize a horse with colic because one could never tell if he was going to make it or not. A serious colic crisis of an intestinal twist or unyielding impaction was a death sentence in those times.

While colic still remains a major killer of horses, today a surge in sophistication of medical, surgical, and anesthetic techniques gives horses a greater chance to survive colic than ever before. Facilities for equine abdominal surgery exist at university veterinary teaching hospitals and in many private clinics throughout the country.

In managing a colic crisis today, whether in the field or at a clinic, a veterinarian has a wealth of expertise from which educated decisions can be made. Although a specific diagnosis is only achieved in about one-quarter of all colic cases, information obtained from a thorough physical exam and diagnostic procedures can hasten a decision to apply aggressive medical intervention or to send a surgical candidate to the operating table. For horses requiring surgery, survival rates are directly related to the severity of the problem and the time span between the onset of colic and surgical correction.

To arrive at a timely diagnosis and medical management, a coordinated team effort must be rallied between an owner and a veterinarian, with a surgical staff on standby if needed.

It is a helpless feeling to watch a horse in pain and distress without being able to do anything about it other than to call for the vet. If your horse does colic, you as the owner have a very important role to play.

Signs to Watch For

Sensitivity to a horse's changing mood can detect subtle and early stages of colic. Rather than waiting for your horse to exhibit marked signs of pain, you should summon a vet immediately upon finding your horse depressed, off feed, or lying down at odd times or in odd postures. Obvious or persistent expressions of pain by a horse affirms a need for veterinary help.

A colicky horse might paw the ground, kick or bite at his belly, roll his upper lip (flehmen), yawn repeatedly, or grind his teeth. He might stretch as if to urinate, or turn his head as if pointing to his abdomen. As pain progresses, a horse might lie down, get up, and lie down again to try and relieve the agony in his belly. Vigorous rolling on the ground, self-inflicted trauma, or a soaking sweat are signals of severe distress, as are poor capillary refill time or poor coloration (brick red or white) of the gums. Prompt recognition of a problem, with immediate administration of medical therapy, can often correct a colic crisis before it turns into a problem requiring surgery. The first thing to do when you notice your horse is feeling poorly is to pick up the phone to call your veterinarian.

Interpreting Your Horse's Pain

While waiting for medical help to arrive, you can do a few things to help your horse ignore his discomfort. In the initial stages of colic, trotting a horse on a longe line for 10 or 15 minutes can relieve the crisis if it is a gaseous or spasmodic episode (sudden, violent, involuntary contraction of a muscle or a group of muscles, attended by pain and interference with function). You might hear him pass gas as he trots, and hopefully after the brief exercise, he will feel more comfortable and the crisis will be over. If severe pain is evident during exercise, it should be discontinued.

If the horse is still painful after trying this strategy, a horse in mild pain should be allowed to rest quietly if he will do so, either standing or lying down. In the old days, horse owners thought there was value in walking a horse for hours. In fact, prolonged forced movement can be counterproductive. Walking or trotting a horse for lengthy periods saps valuable energy reserves needed to combat the crisis--for both horse and owner.

Although each horse has a different threshold for pain, intestinal pain is overbearing to any individual, making painful signs and mental attitude valuable diagnostic aids. If a mildly painful colic persists for more than eight to 12 hours, or if it recurs intermittently during that time, or if intravenous fluids and pain-relieving medications are not correcting the problem, it is probably time for surgery. If a horse has experienced repeated episodes of colic with no specific diagnosis attained, it could be time for exploratory surgery of the abdomen to identify the source of a recurrent problem. Severe or unrelenting pain despite the presence of pain-relieving medications makes a strong argument for the need for surgery.

A painful horse is difficult to handle at times as he might throw himself to the ground or roll violently in an effort to relieve his plight. A horse like this might require forced walking to keep him distracted and somewhat controlled until help arrives. Due to the unpredictability and uncontrollable nature of an extremely violent colic, stay as clear of the horse as possible. Be attentive to the danger of being wedged in a stall corner with the horse. Get the horse on his feet if feasible, and move him to a large area or grassy spot where he is least likely to inflict injury to himself and people.

Communicating with the Vet

The greatest contribution you can make to assist your veterinarian in arriving at a treatment plan is to provide detailed information. Valuable information is learned from the age, sex, breed, and previous and current geographic location of a horse. Specific problems exist in certain areas of the country, and age-related syndromes also occur. Examples include sand colic in certain geographical locales, enteroliths (intestinal stones) in certain parts of the country, lipomas (fatty tumors) in older horses, or large colon torsions (twists) in broodmares which have recently foaled.

Discuss the horse's diet and any recent changes in nutrition, availability of water, exercise routines, or recent transportation of the horse. Deworming schedules, medications your horse currently is receiving, and past illness or surgery are important details to tell your veterinarian. An overview of occurrences in your horse's life in recent hours and days is of paramount importance. Have there been any significant changes in the horse's routine or diet? When was the last noted bowel movement? What was its consistency? When did you last notice your horse eating? When did your horse's demeanor change? Pinpointing the onset of pain or its discovery defines a time period and progression of events pertinent to decisions regarding necessary therapy.

Colic Related to Non-Intestinal Problems

Other issues can cause a horse to look like he is colicking when in fact his intestines are just fine. Some examples might be the horse which is tying-up with muscle cramps, a mare starting labor for foaling, a horse with pleuropneumonia (inflammation of the lungs and the membranes covering the lungs), or a horse which is choking. Even a horse with laminitis might display colic-like signs. The important thing is to see if the horse will rise from the ground, if he will eat if offered food, and to gather all the vital signs you can so that you can intelligently relay this information to your veterinarian when you call.

Vital Signs

Some physical exam parameters can be monitored by you throughout a colic ordeal, such as the horse's degree of pain and mental attitude. Also check:

  • Rectal temperature;
  • Respiratory rate and character;
  • Heart rate, pulse rate, and pulse strength;
  • Color and capillary refill time of mucous membranes;
  • Moistness of mucous membranes and skin elasticity (to roughly estimate dehydration); and
  • Quality and frequency of intestinal sounds in all quadrants.

Each of these parameters is important to the overall clinical picture. With practice, you can learn to examine a horse and recognize when signs differ from those found when your horse is in a normal state. A study conducted by the Morris Animal Foundation concluded that color of the mucous membranes has a significant relationship to survival. Because mucous membrane color and capillary refill time reflect blood perfusion through the body, they correlate well to development and progression of shock. Shock is closely associated with surgical colic syndromes, such as strangulating obstructions of the bowel or very serious obstructions.

Your vet will evaluate all these physical parameters upon arrival. To further assist in arriving at a diagnosis of what is causing the colic, he/she will perform a rectal examination. This procedure entails a careful, systematic palpation of bowel segments for position, tone, and contents of each accessible loop of intestine. Gas-distended intestines might point to a surgical condition, particularly if loops of small intestine are abnormally distended. Displacement of portions of the large colon can be felt. Presence or absence of feces in the rectum is noted.

Manure, if present, is examined for information. Are the fecal balls of normal size and consistency, or are they firm or dry, indicating dehydration? Are the feces coated with mucus, indicating delayed passage of the feces? Is the manure soft or of a diarrhea consistency? An easy check for sand in the manure can be done by placing six fecal balls in a plastic glove and adding water. If more than one tablespoon of sand settles out, that is significant, but if no sand is found in that sample, that doesn't mean there isn't any. (Also, it is common to see intermittent diarrhea or soft stools in horses that chronically ingest sand.)

If gas-distended loops of intestine are felt on rectal exam, if a displacement is obvious, or if an impaction is found, a veterinarian can make a definitive diagnosis. The original cause might remain elusive, but the anatomical problem can be defined. Coupling the findings of a rectal exam with cardiovascular parameters and lack or presence of intestinal activity provides a veterinarian with concrete information regarding the need for aggressive medical treatment or surgery.

If a horse has colic, the veterinarian will pass a nasogastric tube into the horse's stomach. Smooth muscles lining the esophagus do not allow a horse to burp or vomit, so large quantities of gas or fluid can accumulate within the stomach, contributing to pain and cardiovascular compromise. A stomach tube allows an avenue for escape of any painful gas and fluid pressures in the stomach. This improves blood flow through a distended bowel and to the heart.

Copious quantities of fluid (more than 0.5-3.0 gallons, or 2-12 liters) drained through a stomach tube indicate stagnation or obstruction of the small intestine, possibly (but not always) representative of a surgical condition. Not only does a stomach tube provide valuable diagnostic information, but it is also a means to administer intestinal protectants, laxatives, fluids, and electrolytes. Based on the evaluation of intestinal motility, your veterinarian will decide if it is safe to administer something via stomach tube. What to give is determined from specific rectal exam findings and the thorough physical exam.

If a horse poses a questionable surgical case, your veterinarian might obtain a sample of peritoneal fluid by inserting a needle into the abdominal cavity (a procedure called abdominocentesis). This is a relatively painless procedure, with a horse only responding to the needle prick as it passes through the skin. Examination of peritoneal fluid is not always a reliable test for a decision for surgery, but if the color is abnormal or the protein content of the peritoneal fluid is higher than normal (indicating damaged intestine or an infection in the abdomen), then surgery is most likely indicated. Straw-colored peritoneal fluid is normal, whereas pink or orange peritoneal fluid signifies devitalization of an intestinal segment and the need for surgery or euthanasia.

In three-quarters of all colic cases, a definite diagnosis is not achieved. Continual observation and monitoring of a horse with an unspecified source of colic by both owner and veterinarian is essential until the horse responds to medical therapy, or a decision is made to go to surgery.

Bowel Abnormalities Leading to Colic

Gaseous or spasmodic colic is similar to how you feel when you eat too rich a meal and experience gas pain. Similarly, your horse might experience gaseous colic from excess food fermentation. Copious amounts of grain, or or abrupt changes to diets rich in alfalfa or other legumes, predispose a horse to this kind of colic.

A simple obstruction develops from foreign bodies, sand, enteroliths, packed food material, or compression adjacent to the bowel from adhesions, tumors, or abscesses. Pain is often mild or intermittent, but as a mechanical obstruction persists, the buildup of gas and fluid in the bowel increase distention, pressure, and pain. The lining of the intestine begins to degenerate, allowing release of bacteria and toxins into the bloodstream. If instituted early on, therapy with pain-relieving medications and massive quantities of intravenous fluids (5.3-10.6 gallons, or 20-40 liters) might assist in softening and moving a feed or sand impaction on through. However, if such a colic persists for more than eight to 12 hours, or if a horse begins to deteriorate in cardiovascular status, surgery might be indicated.

In a study by Nat White, DVM, Dipl. ACVS, at the Marion duPont Scott Equine Medical Center in Virginia, an interesting piece of information was discovered on the operating table: Most cases of intestinal torsion or displacement appeared to be precipitated or associated with an impaction in the right dorsal colon (a section of the large intestine). It is speculated that a large food mass might precipitate the descent of the colon in the abdomen, whereupon it can twist on its axis or tangle in a knot. An impaction occurs for many different reasons, but one primary reason can be attributed to anything that causes the intestines to shut down for an extended period of time. This could be something as simple as rigorous exercise, particularly when coupled with the inevitable dehydration that accompanies travel and competitive events.

Sand colic can develop as an irritant to the bowel lining or as a simple obstruction. About 35% of horses with sand colic develop diarrhea before the onset of painful signs. In some horses, the only presenting signs might be depressed appetite and/or weight loss. Performance might suffer because of chronic discomfort or reduced nutrient efficiency. Other horses experience low-grade, mildly painful bouts of colic that are intermittent, but recurrent. Sometimes a colic crisis is precipitated during or after riding, possibly because the sandpaper-like abrasion stimulates painful spasms of the intestine.

Horses can ingest up to 2 1/2% of their body weight each day. This can translate into up to 25 pounds of roughage per day for a 1,000 pound horse. If the diet lacks fiber, a horse will seek it out in the form of board fences, weeds, or dirt. Also, a fiber deficiency limits normal stimulation of the large colon, resulting in a more sluggish intestinal motility that might allow sand to precipitate out into the intestine. Feeding adequate amounts of roughage (such as hay or grass), or feeding at frequent intervals, can decrease aberrant behavior such as licking the ground or dirt eating, called pica. The most effective means of limiting the development of sand colic is to feed plenty of good-quality hay to promote efficient intestinal activity. Avoid overstocking pastures to keep ample forage available so horses are not forced to consume dirt. Also, maintain clean, fresh water supplies to encourage drinking, which in itself promotes gastrointestinal health and normal motility.

A displacement refers to colic associated with a loop or more of bowel that has moved out of its normal position. Many intestinal displacements will rectify themselves with medical treatment if bowel motility can be restored with IV fluids. In some instances, no matter how aggressive the therapy, the displaced bowel will become twisted or entrapped, necessitating surgical intervention.

A strangulation obstruction usually is accompanied by an acute and severe onset of pain. In these cases, torsion or volvulus involves twisting of a loop of bowel, which completely blocks off its blood supply. Another possible type of strangulation obstruction occurs if a piece of bowel is incarcerated (trapped) through an opening like a diaphragmatic hernia, an umbilical or scrotal hernia, or through a tear in the mesentery (the membranes that connect the intestines and their appendages to the dorsal or upper wall of the abdominal cavity).

An intestinal lipoma is a fatty tumor on a stalk that can wrap around a loop of bowel, thus strangulating it. The pelvic flexure (a portion of the large colon on the left side) can become entrapped behind the ligament of the spleen, which is known as a nephrosplenic entrapment. If a loop of bowel telescopes inside itself--called an intussusception--the blood supply is interrupted and that area of the bowel begins to die.

In previous decades, postmortem exams of colic deaths revealed that 90% suffered from damage to intestinal blood vessels due to migration of Strongylus vulgaris larvae. Occlusion of blood vessels by larvae and clots created by their presence resulted in a syndrome known as a non-strangulation infarction (death of tissue due to a local lack of oxygen). In these cases, blood supply to the bowel is obstructed, although initially, the bowel itself was in normal health. As blood flow ceases, intestinal motility is disrupted to affected loops of bowel. The end result mimics a strangulation obstruction due to accumulation of gas, fluid, and toxins as bowel degenerates and shock develops. Due to a vast education program and implementation of effective deworming drugs at frequent intervals, parasites are a far less common cause of fatal colic in horses today.

Gastric ulcer syndrome can cause intestinal pain with the potential for colic. Ulceration of the stomach or the right dorsal colon can occur due to physical or behavioral stress, or due to long-term administration of non-steroidal anti-inflammatory medications like flunixin or phenylbutazone.

The Bottom Line

There are many types and causes of colic pain in horses, ranging from mild belly aches to fatal damage. Recognizing signs early and communicating the status and history of your horse to your veterinarian will increase your chances of catching the problem early enough for a successful outcome. 

(horse at rest)
Mucous membranes (gums, sclera of the eye, or a mare's vulvar lips) Press a fingertip to the membranes to blanch away the color Refill time should be no more than two seconds Pale membranes with slow refill time Inadequate cardiovascular circulation that might precede development of shock
Brick-red membranes with rapid refill time of less than one second Shock. Horses in shock from colic require rapid anti-shock therapy with drugs, intravenous fluids, and surgery
Blue or purple mucous membranes Severe, irreversible shock with a grave prognosis. The horse will not likely survive anesthesia or surgery
Heart rate Best taken with a stethoscope on the left side of the horse's chest, just behind the elbow. Each "lub dub" is considered one beat. You also can take the pulse from the lingual artery, on the bottom side of the jaw where it crosses over the bone. Take the pulse for 15 seconds and multiply by four to determine the heart rate in beats per minute. The pulse should be bounding and strong 30-40 beats per minute

40-60 beats per minute


Heart rate that persists between 60-80 beats per minute for more than 15 minutes Severe dehydration or the beginning stages of shock
Greater than 80 beats per minute in a colicky horse Horse is in shock and is in desperate need of surgical intervention or intensive care. Survival rate on these types of cases is only about 25%
Greater than 100 beats per minute in a colicky horse Grave prognosis with a very low survival rate (less than 10%)

Respiratory rate

The respiratory rate (RR) can be taken by watching the horse's chest move in and out (each inhale/exhale is one breath) or feeling the air come out of his nostrils. A stethoscope can be used. Breaths should sound clear 12-24 breaths per minute depending on the ambient temperature Rapid, shallow breathing Pain, fever or severe alterations in metabolic status of the horse
Rectal temperature Shake the thermometer down if using the glass/mercury kind, and place a small amount of lubricant (petroleum jelly or KY Jelly) on the thermometer before inserting into the anus 98-101.2°F Fever Endotoxemia, severe dehydration, or a septic condition within the abdomen or thorax
Low body temperature with cold and clammy limbs and a cold muzzle Shock
Intestinal sounds Use a stethoscope to listen to both sides of the flank and on the abdominal midline at the level of the girth near the sternum At least two rumbling/ gurgling/ tinkling sounds should be heard each minute over each quadrant of both sides of the flanks No sounds Abnormal gut motility requiring immediate treatment   
Sound similar to a pebble falling down a well Gas in the bowel
Squeaky noises An attempt at peristaltic (successive waves) GI movement with no progressive move-ment of material though the intestines
Excessive amount of intestinal noise Spasms or hyperactivity due to irritation in the bowel, or efforts to correct an obstruction
Sound similar to a roiling surf on a sandy beach or sand moving in a paper bag Sand colic


Despite all of the advances in modern veterinary medicine, colic is still the number one killer of horses. In an attempt to provide our horses with the best, we have inadvertently interfered with an efficient digestive adaptation that developed over millennia. Horses are at their digestive best when foraging on dried grasses scattered over arid ground and roaming in search of sustenance. The horse evolved to intermittently snack throughout the day, yet we place him in confined spaces and twice daily supply him with abundant food that is dried and in a relatively concentrated form. It is a wonder that horses have as little colic as they do.

Unequivocally, it is agreed that the most effective way to prevent colic is to minimize changes in your management practices. Horses are creatures of habit; they thrive on routine, both mentally and physically. The most appropriate means of saving your horse from colic is for you to apply excellent preventive management.

  • Provide clean water always. Make sure it remains unfrozen in winter.
  • Keep your horse's diet consistent, and feed at least 60% of his diet (by weight) as roughage (hay or pasture). High-grain diets increase colic risk by three to four times.
  • Avoid changes in feed when possible. There is a quadruple increase in colic risk when diet is changed.
  • Feed good-quality hay, not too coarse and not too fine. Avoid dust and mold.
  • Use feeding systems that minimize eating directly off the ground. The best technique is a feeding system that prevents your horse from spreading hay through the dirt.
  • Feed psyllium products for five to seven consecutive days each month to move dirt and sand through the bowel if sand colic is a problem in your area.
  • Implement an aggressive deworming program with regular fecal examinations and dosing with a deworming medication every four to eight weeks as indicated by the fecal examination. Dose appropriately to your horse's body weight and make sure all of the medication is ingested.
  • Pick up manure in paddocks at least twice a week to minimize load of infective parasitic larvae.
  • Have yearly dental exams and teeth filing performed by your veterinarian to enable your horse to adequately grind his feed.
  • Allow your horse ample exercise, either with turn-out or under saddle.

By recognizing an evolutionary need for horses to frequently eat small amounts of good-quality fiber, feeding practices can be modified to promote improved health of the digestive system and improved mental happiness. A horse performs better in all ways if his natural urge to constantly nibble is satisfied. This is accomplished by providing free-choice grass hay, and only supplementing hard-working individuals or difficult keepers with alfalfa, corn oil, and limited grain. A salt block and adequate water should be available at all times. This uncomplicated diet minimizes sand ingestion, the risk of laminitis, obesity-related strangulating lipomas (fatty tumors), and colic that results from feeding richer foodstuffs.--Nancy Loving, DVM


A horse's intestinal tract spans 70-90 feet in length, with abrupt changes in its diameter and direction. With interruption of normal waves of contraction (peristalsis) in the bowel, excessive gas or fluid can accumulate in the gut. As feed fermentation continues, gas must be able to move toward the rectum or it will build within the intestines, with pain resulting from over-distention. Gas in the intestines, or the added weight of fluid, along with abnormal peristaltic contractions, brings on a displacement in the positioning of loops of bowel.

Bacterial overgrowth develops with stagnation from obstructions or displacements. Eventually, bacteria begin to die, releasing endotoxins (poisonous components of the cell wall of Gram-negative bacteria) that contribute to dehydration, shock, laminitis, and potential death.

A main objective in medical therapy is to restore normal motility to the intestines, not only to move gas, fluid, and food through the tract, but also to prevent sequestration of vital body fluids within a stagnant bowel. If intestinal fluids are not absorbed into the circulatory system, a horse progressively dehydrates and suffers serious fluid and electrolyte imbalances. Blood supply is further compromised due to mounting pressures and tension on blood vessels throughout the abdominal cavity. Over time, with diminished circulating blood volume through the body, hypovolemic (diminished fluid volume) shock compounds the crisis.

When addressed rapidly and effectively, many cases of colic are resolved with appropriate medical treatment. Rather than an owner administering analgesic (pain-killing) drugs and waiting to see if a horse responds, a veterinarian should be summoned. While awaiting the veterinarian's arrival, vital signs can be recorded by the owner to be used for comparison to a veterinarian's findings. (These include heart rate, respiratory rate, rectal temperature, and color and refill time of the mucous membranes, as described in "Normal and Abnormal Vital Signs" on page 54.)

If you are tempted to give your horse drugs before your veterinarian arrives, consider that sedatives or non-steroidal anti-inflammatory drugs often mask pertinent information about your horse's status. This could delay a decision for aggressive medical treatment or to send a horse to surgery. These drugs should only be administered by a veterinarian after a thorough examination or on your veterinarian's orders. Delays in surgical intervention are believed to be the most common cause of surgical failure.--Nancy Loving, DVM

About the Author

Nancy S. Loving, DVM

Nancy S. Loving, DVM, owns Loving Equine Clinic in Boulder, Colorado, and has a special interest in managing the care of sport horses. Her recent book, All Horse Systems Go, is a comprehensive veterinary care and conditioning resource in full color that covers all facets of horse care (available at or by calling 800/582-5604). She has also authored the books Go the Distance as a resource for endurance horse owners, Conformation and Performance, and First Aid for Horse and Rider in addition to many veterinary articles for both horse owner and professional audiences.

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